Update Aloha Editor to jQuery UI version

Current version of Aloha used in FEE is 0.20.16.

New version of Aloha replaces the huge ExtJS library with jQuery UI, which also comes bundled with WordPress. The problem is that the jQuery UI code is embeded directly into the aloha.js file: alohaeditor/Aloha-Editor#779

[keeping the actual Aloha file updates out of the pull request until the very end, to avoid bloating the diff]